, the courtly Washington lawyer is a leading expert on campaign finance law — not the kind of material that generates a lot of laughs.

So the fact that he's appeared seven times on

"The Colbert Report"

in the last year, helping host

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Stephen Colbert

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set up his own "super PAC" as part of a mischievous political parody, underscores an unexpected development in the 2012 presidential race:

Super PACs have seized the zeitgeist.

An indirect outgrowth of the Supreme Court ruling in the 2010 Citizens United case, the independent political groups have mushroomed in the last year. They are now dominating not just the action in key primary states such as South Carolina, but the political conversation. In the last month, the number of

Google

searches for the term "super PAC" was about five times higher than the last year's monthly average.

Spending by such organizations has exceeded $27 million already this year, according to the FEC, much of it going to biting television ads. Pummeled by super PACs aligned with their rivals, the Republican presidential contenders are now loudly denouncing their influence.

Former Massachusetts Gov.

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Mitt Romney

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said in recent days that all of the candidates wished the outside organizations would disappear and that their outsized sway was "a very bad idea."

Former House Speaker

Newt Gingrich

was forced to disavow an error-riddled

documentary

aired by a super PAC run by his former aides, while he and former Pennsylvania Sen.

Rick Santorum

have had to defend themselves against attacks by Restore Our Future, a pro-Romney super PAC. At a campaign stop in Columbia, S.C., this week, Santorum accused Romney of sending "his henchmen" to spread disinformation.

The complaints mark a sharp turnabout for

Republicans

, who had largely heralded the Citizens United decision, which allowed unlimited corporate and union spending on campaigns. (The campaigns themselves remain under strict fundraising limits.)

The candidates are not opposed to unlimited fundraising but, once confronted with how the decision is playing out, have blamed one another, not the court.

"This particular approach, I think, has nothing to do with the Citizens United case," Gingrich said on

MSNBC

this month. "It has to do with a bunch of millionaires getting together to run a negative campaign, and Gov. Romney refusing to call them off."

Most of the major super PACs are run by longtime associates of the candidates, but their ostensible independence allows them access to the unlimited donations. That has led to eye-popping contributions by billionaires such as casino magnate

Sheldon Adelson

, a Gingrich backer, and mutual fund investor Foster Friess, who supports Santorum. Romney's super PAC has been fueled in part by former colleagues from

Bain Capital

.

In South Carolina, super PACs have dropped $6.9 million on TV ads scheduled to run through Saturday's primary, compared with $5.4 million spent on television by the candidates, according to a campaign source familiar with the buys.

"We have never seen anything like this in terms of the amount of money being raised and spent," Potter said. "The scale of it is the surprise. They are spending more than the candidates are."

Critics view the groups as essentially an end-run around campaign contribution limits. Colbert — Potter's frequent host — highlighted the loopholes in the system last week when he declared his candidacy for "president of the United States of South Carolina." With a figurative wink, he handed off control of his super PAC to fellow

Comedy Central

host

Jon Stewart

, renaming it the Definitely Not Coordinating With Stephen Colbert Super PAC.

The group is running an ad urging South Carolinians to vote for businessman

Herman Cain

— who dropped out of the race but is still on the ballot — as a proxy show of support for Colbert. Colbert, who is not on the ballot and separately called for the Cain strategy, suggested Tuesday that he and Stewart "have developed some kind of psychic-twin connection, where one feels what the other is experiencing."

Outside groups played a role in political campaigns before Citizens United – perhaps most famously in 2004, when a group of

. But they operated as so-called 527 organizations — politically active tax-exempt groups that could not expressly advocate for the election or the defeat of a candidate. Groups that wanted to be more explicit in their support had to register as political action committees and could only accept donations of up to $5,000.

That changed two years ago, when a federal court of appeals ruled in a case called Speechnow.org vs. FEC that individual contributions to political advocacy groups could not be limited. The court cited the majority opinion in Citizens United, which concluded that independent spending does not give rise to corruption or the appearance of corruption.

After the Speechnow ruling, the FEC created a new category for such political groups, bestowing them with the ungainly handle "independent expenditure-only committees." A reporter for Roll Call, Eliza Newlin Carney, dubbed them "super PACs" in an early write-up.

Election law attorney Michael Toner said the moniker had increased the spotlight on their activities.